THE NAME Sergei Magnitsky has become synonymous with a United States law that imposes sanctions on Russian individuals who commit serious human rights violations. The actual Magnitsky was a 37-year-old tax law expert who died in a Moscow prison on Nov. 16, 2009, after he exposed Russian officials who fraudulently obtained a $230 million tax refund using corporate shell companies. The companies were seized from a prominent Western investor, William Browder, who employed Magnitsky and is seeking justice for his death. The story of Magnitsky’s defiance and prison ordeal were at the heart of Mr. Browder’s recent bestseller, “Red Notice.”

Not surprisingly, the Magnitsky Act has rankled Russia’s ruling clans. They are furious at not only the individual sanctions but also the way Magnitsky’s name has become a rallying cry for those fighting corruption and human rights abuses. In Russia, Mr. Browder is frequently portrayed on state television as serving the CIA and British intelligence or as puppetmaster of the Russian opposition figure and anti-corruption campaigner Alexei Navalny.

A campaign to discredit Mr. Browder and the Magnitsky Act reached Washington on June 13 with a screening at the Newseum of “The Magnitsky Act — Behind the Scenes,” a lengthy film by Andrei Nekrasov. The film is a piece of agitprop that mixes fact and fiction to blame Magnitsky for the fraud and absolve Russians of blame for his death. The filmmaker uses facts highly selectively. He repeatedly holds up one document as evidence Magnitsky did not identify the fraudsters by name. In fact, in another document, just months before, Magnitsky had identified them repeatedly.

Mr. Nekrasov declares, “Magnitsky wasn’t a whistleblower. Magnitsky did not accuse any police officers. Magnitsky did not even investigate anything.” He adds, “The young man died in a Russian prison. I do not believe it was murder. It was a case of negligence and the Russian system is to blame in many ways, but it wasn’t murder; he wasn’t murdered by the Russian state as Mr. Browder claims.” This is just what President Vladimir Putin and his honchos want the West to hear.

In fact, the presidential human rights council stated in 2011 that Magnitsky “was completely deprived of medical care before his death” in prison and “there is reasonable suspicion to believe that the death was triggered by beating.” Relatives later found his knuckles smashed and bruises on his body, according to Mr. Browder. A document signed by prison authorities on the day he died reports that rubber batons were used against him. Rubber batons don’t hit someone on their own.

The film won’t grab a wide audience, but it offers yet another example of the Kremlin’s increasingly sophisticated efforts to spread its illiberal values and mind-set abroad. In the European Parliament and on French and German television networks, showings were put off recently after questions were raised about the accuracy of the film, including by Magnitsky’s family. We don’t worry that Mr. Nekrasov’s film was screened here, in an open society. But it is important that such slick spin be fully exposed for its twisted story and sly deceptions.